The present invention relates to a test device and a method for carrying out a function test on a communication system, in particular in an aircraft cabin, in particular in the aerospace sector.
Although it can be applied to any sector, the present invention is described in more detail with respect to an aircraft or a passenger aircraft.
Communication systems in aircraft cabins provide communication services or services such as GSM, UMTS, WLAN or the like for the crew of the aircraft or for passengers.
To emit the respective service signal for the corresponding service, a leaky line antenna may be used, which is arranged longitudinally in the aircraft cabin. To test the proper installation and function of the communication system, in particular to ensure the high frequency (HF) signal distribution within the aircraft cabin, a coverage measurement (radio supply measurement) is carried out in each frequency band of the corresponding services by means of an HF spectrum analyser and a measuring antenna at a plurality of different locations in the aircraft cabin. In this case, the measurement results may vary greatly depending on state and configuration of the aircraft cabin and selection of the measuring location. For this reason, the measurement results have to be averaged in a suitable manner and corrected by the respective antenna factors of the measuring antennas used.
A measurement carried out imprecisely or in a faulty manner may under some circumstances lead to predetermined, in particular official limit values being fallen below, evaluate conventional measurements, specially trained staff are also necessary. Such trained staff also have to have experience with HF measurements, in particular. Furthermore, the conventional measurements require special hardware, for example the HF spectrum analyser and the measuring antenna.
In order to be able to carry out the test at any location in the aircraft cabin, HF test signals are conventionally used, which have a power level requiring official approval. This official approval is conventionally necessary as the conventional HF test signals at the power levels used can still also be measured outside the aircraft and can potentially cause disruption of other services.
To solve these problems, a test device for automatically carrying out a function test on the communication system is known to the applicant in-house.
This in-house test device contains a transmission path, which has at least one leaky line antenna arranged in the aircraft cabin. This test device furthermore has a control device coupled to the transmission path, which has a generating mechanism for generating a broadband noise signal and a transmission mechanism for feeding an HF signal onto the leaky line antenna, the HF signal fed in having a predetermined power level and containing at least the generated broadband noise signal. Furthermore, this test device has a measuring mechanism coupled at a predetermined coupling point to the transmission path for measuring the power level of the HF signal at the coupling point and for providing a measuring signal proportional to the measured power level, and an evaluating means for providing a test result by means of a comparison between the measuring signal provided and a desired signal which depends on the power level of the HF signal fed in.
In this case, the measuring mechanism coupled via the transmission path is also connected to the control device by means of a first line for transmitting the measuring signal from the measuring mechanism to the control device and by a second line for the current supply of the measuring mechanism by means of the control device.
In this case, the first line and the second line have to be installed or laid in the aircraft cabin. A line installation of this type or cabling is disadvantageously expensive in terms of time and cost and furthermore contains the risk of faults in the line installation.
Accordingly, a need underlying to the present invention is to provide an automated function test on a communication system, in particular in an aircraft cabin, in which no additional line installation is necessary.